A standard motor-vehicle trunk latch has as described in commonly owned U.S. Pat. No. 4,892,339 a housing formed with a laterally open recess in which the bolt is receivable, a latch fork formed with a fork seat and with at least one detent, and a fork pivot on the housing supporting the fork for pivoting between a locked and a semilocked position with the seat directed away from the fork pivot and the bolt engaged in the seat and an unlocked position permitting the bolt to enter and exit seat and recess. An operating plate pivotal on the housing about an axis substantially parallel to the fork pivot carries the pivot of a latch pawl which is pivotal on the link plate into and out of a position engaging the detent and thereby retaining the fork in the semilocked position. A motor connected to the operating plate can pivot same about its axis and, when the pawl is engaged with the detent, pivot the fork into the locked position. A door handle and a link connected between the handle and the pawl can pivot same out of engagement with the detent in any position of the fork.
Thus with this system the operating plate is pivoted to power-close the door, thereby pivoting the pawl and using this pawl to push the fork around into the fully locked position. The user of the latch need merely push the door to into the semi-locked position; the motor will take over from here and pull the door fully to into the locked position.
The axis of the operating plate is coaxial with the fork pivot. In this manner the motor force is transmitted with force-multiplying lever action to the fork. In addition the motor carries an orbital crank and a link has one end pivoted on the crank and an other end formed with a slot. A pin on the plate engages in the slot. Thus the plate can move limitedly relative to the link due to the lost motion created by the slot, but the motor will still be able to effectively act virtually directly on the operating plate.
The door handle of this system is a two-arm lever pivotal on the housing between an open and a closed position and has a lower end provided with a pivot coaxial in the open position with the plate pivot axis. The link is pivoted on the pivot of the handle lower end and provided with an opposite end having a slot and the pawl is provided with a pin engaging in the link slot. Furthermore the motor is a small electric motor which, in spite of being a low-wattage unit, can easily pull a door shut with enough force to completely eliminate air or water leaks around it.
While such an arrangement is relatively effective it is fairly complex. Furthermore manual actuation of the latch is difficult and impossible when the latch is partially opened.